Increased temperature sensitivity and divergent growth trends in circumpolar boreal forests

[1] Tree rings have been used to both reconstruct past climate, and to estimate and project carbon uptake of forest ecosystems. Here we show that large groups of trees of the dominant tree species within widely-distributed circumpolar forest sites show opposing growth trends during recent warming. These opposing growth trends are present at a sub-chronology level and, if averaged into chronologies, may have contributed to the widely reported overall decreased temperature sensitivity of high-latitude chronologies over recent decades. Unlike previous studies, we find that temperature sensitivity has actually increased for most individual trees at these sites. This recent, widespread divergence in growth response seems unique over the past three centuries, and may relate to different microsite responses of individual trees to temperature-induced drought stress or other factors. This divergence needs to be taken into account in dendroclimatic reconstructions, estimations of global warming impacts, and carbon uptake projections.

[1]  Bruce P. Finney,et al.  Reduced growth of Alaskan white spruce in the twentieth century from temperature-induced drought stress , 2000, Nature.

[2]  Gordon C. Jacoby,et al.  Long-Term Temperature Trends and Tree Growth in the Taymir Region of Northern Siberia , 2000, Quaternary Research.

[3]  M. Hughes,et al.  Northern hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations , 1999 .

[4]  Martin Wilmking,et al.  Longitudinal variation of radial growth at Alaska's northern treeline—recent changes and possible scenarios for the 21st century , 2005 .

[5]  Edward R. Cook,et al.  Low-Frequency Signals in Long Tree-Ring Chronologies for Reconstructing Past Temperature Variability , 2002, Science.

[6]  R. Holmes.  Computer-Assisted Quality Control in Tree-Ring Dating and Measurement , 1983 .

[7]  K. Briffa,et al.  Large-scale temperature inferences from tree rings: a review , 2004 .

[8]  Edward R. Cook,et al.  Methods of Dendrochronology , 1990 .

[9]  P. Ciais,et al.  A Large Northern Hemisphere Terrestrial CO2 Sink Indicated by the 13C/12C Ratio of Atmospheric CO2 , 1995, Science.

[10]  Ranga B. Myneni,et al.  Thresholds for warming‐induced growth decline at elevational tree line in the Yukon Territory, Canada , 2004 .

[11]  F. H. Schweingruber,et al.  Reduced sensitivity of recent tree-growth to temperature at high northern latitudes , 1998, Nature.

[12]  Konrad A Hughen,et al.  Arctic Environmental Change of the Last Four Centuries , 1997 .

[13]  Makiko Sato,et al.  GISS analysis of surface temperature change , 1999 .

[14]  Gordon C. Jacoby,et al.  Tree ring width and density evidence of climatic and potential forest change in Alaska , 1995 .

[15]  I. C. Prentice,et al.  Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model , 2003 .

[16]  William,et al.  Tree Rings , 1935, Science.

[17]  Harold S. J. Zald,et al.  Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholds , 2004 .

[18]  M. K. Hughes,et al.  Influence of snowfall and melt timing on tree growth in subarctic Eurasia , 1999, Nature.